(() => {
  // 通过接口实现类的接口
  interface Obj{
    fn():void
  }
  class Person implements Obj {
    fn() {
      console.log(666)
    }
  }
  console.log((new Person()).fn())

  // 类继承多个接口
  interface Geme{
    setfn():void
  }
  class son implements Obj, Geme{
    fn() {
      console.log(777)
      return this;
    }
    setfn() {
      console.log(888)
    }
  }
  console.log((new son()).fn().setfn())

  // 接口继承接口
  interface Sum extends Obj, Geme{

  }

  class SOngyu implements Sum{
    fn() { }
    setfn(){}
  }
  new SOngyu()
})()